Towards implementation of FMCW LiDAR with quadrature modulator architectures in generic InP photonic integration technology

Two architectures with quadrature modulation in a generic InP platform are proposed for realizing frequency-modulated continuous-wave (FMCW) LiDAR. Simulations are used to compare the architectures in terms of tolerance to optical imbalances, insertion loss, chip footprint, and ease of control. The parallel architecture is more resilient to imbalances (~0.82 dB power imbalance for 20 dB ER) than the cascaded architecture (~0.63 dB power imbalance for 20 dB ER)

High Density Integration of Semiconductor Optical Amplifiers in InP Generic Photonic Integration Technology

We present experimental studies of semiconductor optical amplifiers (SOA) with a high integration density in an InP generic photonic integration platform. We study the active-passive butt joint integration of dense arrays of active islands with widths ranging from 2 to 30 μm, and pitches ranging from 4 to 270 μm. We show that there is significant room for increasing the density of active island arrays while keeping a similar growth rate enhancement in between the active islands. The impact of narrow active islands on SOA performance is also studied with an array of Fabry-Pérot lasers fabricated in a commercial generic platform. We demonstrate the manufacturability of lasers with a pitch of 25 μm and evaluate individual device performance. Threshold currents and slope efficiencies are not impaired with narrow active island down to 6 μm, with values of 19-26 mA and 0.08-0.15 W/A respectively.</p

Demonstration of low RMS differential phase noise across C-band for integrated, amplifying optical phased arrays

We experimentally demonstrate low RMS differential phase noise (&lt;10mrad) across C-band in optical phased array channels integrated with in-line semiconductor optical amplifiers using a generic InP photonic integrated platform without active phase locking

Demonstration of low RMS differential phase noise across C-band for integrated, amplifying optical phased arrays

We experimentally demonstrate low RMS differential phase noise (&lt;10mrad) across C-band in optical phased array channels integrated with in-line semiconductor optical amplifiers using a generic InP photonic integrated platform without active phase locking

Demonstration of low differential phase noise for optical phased arrays with optical amplification

Optical phased arrays (OPAs) are key enablers for light detection and ranging (LiDAR) in autonomous vehicles, free space optical communications, imaging and coherent beam combining. Active OPAs (with amplitude and phase control) allow the control of individual channel gains along with phases for enhanced control of far-field beam pattern. Path length variations and noise from amplifiers degrade the differential phase noise between the OPA channels, which is a key performance indicator that determines the far-field performance in terms of power in the main lobe, extinction of side lobes and pointing error. Conventionally, in fiber-based platforms, multiple phase locked loops are required to reduce the differential phase noise by locking the channels.In this work, we investigate the differential phase noise in an InP active OPA and demonstrate less than 10 mrad differential phase noise corresponding to a stability better than λ/600. To the best of our knowledge, this is the first demonstration of low differential phase noise in an active OPA with amplification in a photonic integrated platform. This result enables on-chip OPA amplification in the InP platform without active locking, thus reducing the system complexity and power consumption

Efficiency-boosted semiconductor optical amplifiers via mode-division multiplexing

Semiconductor optical amplifiers (SOAs) are a fundamental building block for many photonic systems. However, their power inefficiency has been setting back operational cost reduction, circuit miniaturization, and the realization of more complex photonic functions such as large-scale switches and optical phased arrays. In this work, we demonstrate significant gain and efficiency enhancement using an extra degree of freedom of light—the mode space. This is done without changing the SOA’s material design, and therefore high versatility and compatibility can be obtained. Light is multiplexed in different guided modes and reinjected into the same gain section twice without introducing resonance, doubling the interaction length in a broadband manner. Up to 87% higher gain and 300% higher wall-plug efficiency are obtained in a double-pass SOA compared to a conventional single-pass SOA, at the same operating current, in the wavelength range of 1560–1580 nm

Integrated optical phased array with on-chip amplification enabling programmable beam shaping

We present an integrated optical phased array (OPA) which embeds in-line optical amplifiers and phase modulators to provide beam-forming capability with gain and beam steering in the 1465–1590 nm wavelength range. We demonstrate up to 21.5 dB net on-chip gain and up to 35.5 mW optical output power. The OPA circuit is based on an InP photonic integration platform and features the highest measured on-chip gain and output power level recorded in an active OPA (i.e., with amplification), to the best of our knowledge. Furthermore, the OPA enables the independent control of both amplitude and phase in its arms and through this we demonstrate programmable beam shaping for two cases. First, we carried out a Gaussian apodization of the power distribution profile in the OPA emitter waveguides, leading to 19.8 dB sidelobe suppression in the far-field beam, which is the highest value recorded for active OPAs, and then we demonstrated beam forming of 0th, 1st, and 2nd order 1D Hermite–Gaussian beams in free-space

Artificial optoelectronic spiking neurons with laser-coupled resonant tunnelling diode systems

We report a spiking artificial optoelectronic neuron based on a resonant tunnelling diode (RTD) coupled to a photodetector (receiver) and a vertical cavity surface emitting laser (VCSEL, transmitter). We experimentally realize this O/E/O system, and demonstrate optical spiking with a well-defined, adjustable excitability threshold

Tuneable presynaptic weighting in optoelectronic spiking neurons built with laser-coupled resonant tunneling diodes

Optoelectronic spiking neurons are regarded as highly promising systems for novel light-powered neuromorphic computing hardware. Here, we investigate an optoelectronic (O/E/O) spiking neuron built with an excitable resonant tunnelling diode (RTD) coupled to a photodetector and a vertical-cavity surface-emitting laser (VCSEL). This work provides the first experimental report on the control of the amplitude (weighting factor) of the fired optical spikes directly in the neuron, introducing a simple way for presynaptic spike amplitude tuning. Notably, a very simple mechanism (the control of VCSEL bias) is used to tune the amplitude of the spikes fired by the optoelectronic neuron, hence enabling an easy and high-speed option for the weighting of optical spiking signals in future interconnected photonic spike-processing nodes. Furthermore, we validate the feasibility of this layout using a simulation of a monolithically-integrated, RTD-powered, nanoscale optoelectronic spiking neuron model, confirming the system's potential for delivering weighted optical spiking signals at very high speeds (GHz firing rates). These results demonstrate the high degree of flexibility of RTD-based artificial optoelectronic spiking neurons and highlight their potential towards compact, high-speed and low-energy photonic spiking neural networks for use in future, light-enabled neuromorphic hardware